1. Field of the Invention
The present invention relates to an acoustic wave acquiring apparatus and control method thereof.
2. Description of the Related Art
There has been known an ultrasound apparatus (acoustic wave acquiring apparatus) as an apparatus for acquiring image information of an object. As the ultrasound apparatus described above, Japanese Patent Application Laid-Open No. 2011-103913 (Patent Literature 1: PTL 1) describes an apparatus configured to hold and press the object by two opposing holding plates, and to two-dimensionally scan a probe in a horizontal direction and in a vertical direction in order to acquire an image. In the ultrasound apparatus described above, matching oil is filled between the probe and the holding plate in order to realize an acoustic impedance matching between the probe and the holding plate. The matching oil is retained by an oil seal arranged to enclose the probe. The oil seal has an opening formed on its top surface from which air bubbles mixed in the matching oil can be removed.
International Publication No. WO99/049504 (Patent Literature 2: PTL 2) describes a technique of filling liquid between a member that is mechanically scanned and a fixed member in order to prevent air from entering. The apparatus described in PTL 2 is a projection exposure apparatus including a two-dimensional scanning stage that can realize two-axis scan in the horizontal direction, and a projection optical system that projects light onto a wafer provided on a stage from above. This apparatus is also provided with a liquid supplying apparatus for filling liquid between the surface of the wafer and the bottom surface of the projection optical system, wherein the liquid is supplied between the surface of the wafer and the bottom surface of the projection optical system from a liquid supplying nozzle and a liquid collecting nozzle. When the wafer moves, the supplied liquid goes out, and air might enter. To deal with the problem, the liquid is continuously supplied at all times. Since the position where air enters is different depending upon the moving direction of the wafer, plural supplying nozzles and plural collecting nozzles are provided at each positions corresponding to the moving direction of the wafer. The liquid is supplied from the nozzle corresponding to the moving direction of the wafer out of the plural supplying nozzles. The liquid supplying apparatus has a control unit for a supply amount of the liquid. The supply amount of each of the supplying nozzles on the corresponding positions is adjusted according to the moving speed of the wafer.
PTL 1: Japanese Patent Application Laid-Open No. 2011-103913
PTL 2: International Publication No. WO99/049504